Patent GB-747013-A (GB)
Title: An arrangement for deriving an electrical output signal which is a function of an electrical or mechanical input control signal
IPC: G05B11/01
Filed: 1952-06-30
Abstract: 747,013. Converting; automatic control systems. LABORATOIRES DE PHYSIQUE APPLIQUEE L.E.G.P.A. June 30. 1952 [June 30,1951; Sept. 19,1951; Sept. 19,1951; Nov. 9, 1951], No. 16477/52. Classes 38 (2) and 38 (4). [Also in Groups XXXVI, XXXVII, XXXVIII and XXXIX] An inverter, which may operate as a transducer or as an amplifier, whereby a train of alternating pulses is derived from a source of D.C. comprises a magnetic core 1 with an airgap in which vibrates an armature 3 engaging contacts 4, 5 alternately to complete a circuit through driving winding 7. The armature 3 is polarized by a winding or permanent magnet 2, and the current through the winding 7, derived from D.C. source 12. having resistors 10, 11 connected across it, consists of a train of alternating square-topped pulses A, Fig. 3, each of which reverses the existing attractive force between the armature and the poleface adjacent that contact 4 or 5 through which the pulse is flowing. The load, which may be connected at 14 between one end of winding 7 and the junction of resistors 10, 11 or at 15 in parallel with winding 7 is energized by the pulses whose width is determined by the interval of dwell of the armature on the contacts. When used as an amplifier signal current flowing through control winding 13 unbalances the relay and changes the relative times of dwell on the two contacts so that the alternate pulses become unequal as at B or C, Fig. 3, and the average value of current in winding 7 and load 14 or 15 has a value in one direction or the other determined by the value and direction of the signal. The voltages applied between the armature 3 and contacts 4, 5 may differ. Positive or negative current and/or voltage feedbacks may be provided by connecting one or more further windings on core 1 in series or parallel with winding 7, Figs. 5-7 (not shown). To maintain good fidelity with high gain, two amplifiers I, II (or more) are connected in cascade, the signal coil 22 of II forming the load of I, Fig. 9. For greater stability, a feedback winding 26 on the core of I is connected in series, Fig. 9, or in parallel, Fig. 10 (not shown), with the load. For high input impedance, the signal may be fed to the grid of a triode 29, in whose anode circuit the signal winding 13 is connected, the D.C. component being compensated by D.C. in a further winding 31, Fig. 11. For low input impedance, the signal may first pass through a magnetic amplifier, Fig. 12 (not shown). Several signal currents may be algebraically combined, either by feeding them to the same winding 13, Fig. 14 (not shown) or to separate control windings 13<SP>1</SP>, 13<SP>2</SP>, 13<SP>3</SP>, Fig. 15, or proportional voltages may be combined, Fig. 17 not shown). Potentiometers 43, 44, 49 allow mixing in any desired proportions. Arrangements of two or more amplifiers reciprocally connected so that each controls the output of the other, may give the solution to simultaneous equations. In the arrangement of Fig. 16, where two amplifiers receive equal signals at 48, 55 and equal resistances are connected across windings 7, 7<SP>2</SP>, output currents at 53, 54 form the roots of two linear equations of which the settings of potentiometers 43, 432 and 44, 44<SP>2</SP> are respectively the parameters. By connecting impedances other than linear resistances at various points in the circuit, the transfer law of the amplifier may be made non-linear, Figs. 19-22 (not shown). The input signal or signals may control the speed of a motor 58, whose armature replaces either impedance 14 when a feedback winding 61 is so arranged that the torque is kept constant, Fig. 23, or impedance 15 when the speed is kept constant for a steady signal, Fig. 24 (not shown). The field winding may then replace impedance 14, Fig. 25 (not shown). For constant speed, the motor 58, energized from a second amplifier stage II, may drive a tachometer generator 64 which energizes a feedback winding 66 in stage I, Fig. 26. The use of the amplifier is described in circuits by which the linear or angular motion of one element is made to follow that of another, Figs. 27-33 (not shown), (see Group XXXVIII). The single armature 3 of Fig. 1 may be replaced by two armatures 3<SP>1</SP>, 3<SP>2</SP> joined by an insulating magnetic bar 10<SP>2</SP>, which co-operate respectively with contacts 4, 5, to connect together the cathode and grid of the associated valve 94 or 95 which fires to produce a pulse through a corresponding winding 7<SP>2</SP>, 7<SP>1</SP> from D.C. potential +B. These pulses energize the load which may be connected at 15 between the windings 71, 72 or in series with them, and also move the armature, Fig. 34. Decoupling condensers 98, 99 prevent sparking. Various other arrangements of valves are described, Figs. 35-37 (not shown). There may be no actual breaking of contact, the armature 3 bearing a piece 86, e.g. of tungsten or carbon; whose resistance varies in accordance with the pressure it applies to two contacts 4<SP>3</SP>, 5<SP>3</SP> between which it lies. The output is a train of alternating pulses with no intervals between, and by connecting a resistor 144 or other impedance across winding 7, may be tuned into a nearly uniform continuous current, Fig. 41. A mechanical force such as that due to acceleration when the apparatus is carried by a vehicle, acting on the armature, the fixed contacts or tl e polarizing magnet, may be used instead of an electric signal to control the output of the vibrator which then becomes a transducer, Figs. 43-51 (not shown). A mechanical or electrical bias may be arranged so that the force exerts its effect about a predeter. mined value. The electric bias may be an input signal which co-operates with the mechanical force to control the output. Several forces and electrical signals may be combined, Fig. 55 (not shown), the transducers may be used in similar systems to those described as employing amplifiers, e.g. circuits for solving simultaneous equations, Fig. 66 (not shown), for controlling a motor with speed or torque regulation, Figs. 57, 58 (not shown), and constituting linear to angular motion follow-up systems, Figs. 59-62 (not shown).